Recently, a technology of making a viewer sense a stereoscopic image (a three-dimensional (3D) image) by viewing, from among two images having binocular disparity, a right-eye image with the right eye and a left-eye image with the left eye has generally spread. An apparatus for capturing a stereoscopic image which generates a right-eye image and a left-eye image to make a viewer sense a stereoscopic image tends to include two imaging units in order to generate the right-eye image and the left-eye image.
However, since a precision at which the two imaging units or lenses constituting the two imaging units are formed or assembled varies according to devices, there may exist a difference between an imaging axis set during design and an actual imaging axis in each of the two imaging units, or there may exist a magnification difference between the two imaging units. Accordingly, due to two pieces of image data generated by the two imaging units, an observer may not correctly observe a stereoscopic image. An imaging axis refers to an imaging direction and corresponds to the center of an image (image center) generated by an imaging unit. Such a difference between a set imaging axis and an actual imaging axis or a magnification difference may be corrected by directly adjusting hardware or adjusting a cutout range of obtained image data.
For example, a technology of setting, for image data generated by one imaging unit, a cutout range for cutting out the image data by using an actual imaging axis of one imaging unit as a center, and setting, for image data generated by the other imaging unit, a cutout range by moving a center during cutout (cutout center) by as much as a difference between an actual imaging axis of the other imaging unit and the actual imaging axis of the one imaging unit is disclosed (for example, Patent Reference 1).
However, when a difference between a set imaging axis and an actual imaging axis is corrected by adjusting a cutout range and a cutout center during cutout from image data, the cutout range is limited to a range of the image data. Accordingly, when image data of only one imaging unit is deviated from the cutout center, the cutout range is limited by the deviated cutout center and a range of the image data.